Composite Membranes Research Articles

Aminopropyl functionalized iron-phyllosilicate (AIP) engineered composite membrane for hazardous emerging pollutant treatment

Catalytic degradation of organic foulants using cost-effective and light-independent catalyst in membrane system is a promising technology in advancing the self-cleaning membranes. In this work, we report AIP-clay as an efficient light-independent catalyst in membrane system to degrade the organic foulants. The characterization of AIP-clay and membrane was performed using FE-SEM, ATR-IR, DLS, XPS, AFM, zeta potential, and contact angle measurements. The optimised AIP-clay loaded membrane (0.1AIP-PAN) showed an efficient Fenton-based insitu degradation of fouled dyes and SWW both in dark and light condition. Although, membrane exhibited significant self-cleaning capabilities in presence of light, the efficiency was nearly equivalent in dark condition as well, indicating minimal disparity in performance. The membranes remained stable even after multiple cycles of self-cleaning, with no notable loss in flux or rejection ability. The 0.1AIP-PAN membrane performance was further assessed based on the removal capacity of various salts (18% of NaCl and 38% of MgSO4), dyes (MB, MG, CR, EBT and RBr), SWW (>90%) and pharmaceuticals (>80%). In addition, the AIP-clay loaded membrane was studied for its anti-fouling property via long-term study for SWW with 97.7% FRR while retaining the membrane stability even after 216 h. Therefore, these studies demonstrate the potential self-cleaning in both dark and light, long-term stability and high separation performance of the AIP-clay membranes for diverse applications.

Antimicrobial Ionic Liquids: Ante-Mortem Mechanisms of Pathogenic EPEC and MRSA Examined by FTIR Spectroscopy.

Ionic liquids (ILs) have gained considerable attention due to their versatile and designable properties. ILs show great potential as antibacterial agents, but understanding the mechanism of attack on bacterial cells is essential to ensure the optimal design of IL-based biocides. The final aim is to achieve maximum efficacy while minimising toxicity and preventing resistance development in target organisms. In this study, we examined a dose-response analysis of ILs' antimicrobial activity against two pathogenic bacteria with different Gram types in terms of molecular responses on a cellular level using Fourier-transform infrared (FTIR) spectroscopy. In total, 18 ILs with different antimicrobial active motifs were evaluated on the Gram-negative enteropathogenic Escherichia coli (EPEC) and Gram-positive methicillin-resistant Staphylococcus aureus (MRSA). The results showed that most ILs impact bacterial proteins with increasing concentration but have a minimal effect on cellular membranes. Dose-response spectral analysis revealed a distinct ante-mortem response against certain ILs for MRSA but not for EPEC. We found that at sub-lethal concentrations, MRSA actively changed their membrane composition to counteract the damaging effect induced by the ILs. This suggests a new adaptive mechanism of Gram-positive bacteria against ILs and demonstrates the need for a better understanding before using such substances as novel antimicrobials.

Antibacterial and anti-biofilm activities of antibiotic-free phosphatidylglycerol/docosahexaenoic acid lamellar and non-lamellar liquid crystalline nanoparticles

Infectious diseases, particularly those associated with biofilms, are challenging to treat due to an increased tolerance to commonly used antibiotics. This underscores the urgent need for innovative antimicrobial strategies. Here, we present an alternative simple-by-design approach focusing on the development of biocompatible and antibiotic-free nanocarriers from docosahexaenoic acid (DHA) that has the potential to combat microbial infections and phosphatidylglycerol (DOPG), which is attractive for use as a biocompatible prominent amphiphilic component of Gram-positive bacterial cell membranes. We assessed the anti-bacterial and anti-biofilm activities of these nanoformulations (hexosomes and vesicles) against S. aureus and S. epidermidis, which are the most common causes of infections on catheters and medical devices by different methods (including resazurin assay, time-kill assay, and confocal laser scanning microscopy on an in vitro catheter biofilm model). In a DHA-concentration-dependent manner, these nano-self-assemblies demonstrated strong anti-bacterial and anti-biofilm activities, particularly against S. aureus. A five-fold reduction of the planktonic and a four-fold reduction of biofilm populations of S. aureus were observed after treatment with hexosomes. The nanoparticles had a bacteriostatic effect against S. epidermidis planktonic cells but no anti-biofilm activity was detected. We discuss the findings in terms of nanoparticle-bacterial cell interactions, plausible alterations in the phospholipid membrane composition, and potential penetration of DHA into these membranes, leading to changes in their structural and biophysical properties. The implications for the future development of biocompatible nanocarriers for the delivery of DHA alone or in combination with other anti-bacterial agents are discussed, as novel treatment strategies of Gram-positive infections, including biofilm-associated infections.

Improved Protein Removal Performance of PES Hollow-Fiber Ultrafiltration Membrane with Sponge-like Structure.

The research used polyethersulfone (PES) as a membrane material, polyvinylpyrrolidone (PVP) k30 and polyethylene glycol 400 (PEG 400) as water-soluble additives, and dimethylacetamide (DMAc) as a solvent to prepare hollow-fiber ultrafiltration membranes through a nonsolvent-induced phase separation (NIPS) process. The hydrophilic nature of PVP-k30 and PEG caused them to accumulate on the membrane surface during phase separation. The morphology, chemical composition, surface charge, and pore size of the PES membranes were evaluated by SEM, FTIR, zeta potential, and dextran filtration experiments. The paper also investigated how different spinning solution compositions affected membrane morphology and performance. The separation efficiency of membranes with four different morphologies was tested in single-protein and double-protein mixed solutions. The protein separation effectiveness of the membrane was studied through molecular weight cutoff, zeta potential, and static protein adsorption tests. In addition, the operating pressure and pH value were adjusted to improve ultrafiltration process conditions. The PES membrane with an intact sponge-like structure showed the highest separation factor of 11, making it a prime candidate membrane for the separation of bovine serum albumin (BSA) and lysozyme (LYS). The membrane had a minimal static protein adsorption capacity of 48 mg/cm2 and had excellent anti-fouling properties. When pH = 4, the BSA retention rate was 93% and the LYS retention rate was 23%. Furthermore, it exhibited excellent stability over a pH range of 1-13, confirming its suitability for protein separation applications.

Prompted by surface-engineered honeycomb Turing nanostructures: Reflections on polyamide structure, growth and performance

The robust correlation between the performance of thin-film composite (TFC) reverse osmosis membranes and the polyamide (PA) active layer determines the necessity of precise design of the PA layer, and this regulation primarily involves the surface morphology and internal characteristics of the PA layer. In this study, we fabricated honeycomb Turing structure or nanovoid-rich TFC series membranes using polar/nonpolar organic phase additives. Characterization and simulation results confirmed that the enhancement of membrane performance relied more on the abundant nanovoids within the PA layer rather than the ordered honeycomb lattice surface. Notably, the TFC-nDCE membrane with multilayer nanovoids exhibited an approximately 89 % improvement in water permeability while maintaining satisfactory salt rejection (98.29 %). We emphasized the significant role of nanovoids in the diffusion process of amine monomers and investigated the potential relationship between nanovoids and the degree of surface cross-linking. Building upon this, a new insight into the formation of nanovoids induced by PA anisotropic growth was presented through a careful analysis of the amine monomer diffusion rate and the morphological evolution of nanovoids. The structure-property relationship between internal structures, surface morphologies, and performances was systematically and thoroughly investigated, pointing out the direction for the rational design of TFC membranes.

Nanomorphogenesis of polyamide membranes by regulating activator-inhibitor diffusivity difference

The use of nanofiltration (NF) membranes featuring crumpled polyamide layers with excellent permeance and selectivity is promising for efficient water reclamation. Although diffusion-driven instability has been regarded as the key mechanism for forming crumpled polyamide structures, in-depth analyses of the morphological and structural features of these membranes are still lacking. We used ammonium carboxymethylcellulose (CMC) and glutaraldehyde (GA) to crosslink and form a pH-responsive interlayer to manipulate the interfacial polymerization (IP) process and the microstructures of interlayered thin-film composite (TFNi) membranes. Experimental observations and molecular dynamics simulations indicate a transition point in the spatial patterns from irregular to regular polyamide nanostructures by tuning the diffusivity difference between the reactant monomers in the two immiscible phases during the IP process. Compared with irregularly crumpled TFNi membranes, regularly crumpled TFNi membranes exhibited polyamide layers with higher aspect ratios (i.e., height/lateral dimension), potentially offering an increased filtration area and sufficient nanovoids. TFNi membranes exhibited a 2.5-fold increase in permeance compared to pristine polyamide membranes, along with twice the selectivity (up to 87.2) for Cl−/SO42−. Our work provides molecular insights into the tuning of morphological features and membrane performance of crumpled polyamide membranes.

Multifunctional flexible composite membrane based on nanocellulose-modified expanded graphite/electrostatically spun fiber network structure for solar thermal energy conversion

To enhance the application range of flexible films, it is crucial to rationally design composite films with high stretchability, excellent thermal conductivity, and water resistance. Flexible composite films with nanocellulose (CNF)-modified expanded graphite and spun fibers loaded with phase change materials as the backbone were obtained by electrospinning method. The prepared materials were characterized by good tensile properties (328.32%), high latent heat (107.0 J/g), good thermal stability, high photo-thermal conversion efficiency, good reusability, flame retardant properties, UV resistance and visible light absorption properties. What's more, the performance of the flexible composite membrane is adjustable. The prepared flexible composite membranes are promising in the fields of solar thermal energy conversion, wearable flexible materials and renewable energy utilization.

A BaTiO3@polyacrylonitrile/poly(vinylidene fluoride) nanofibrous composite membrane with high piezoelectricity based on the central combination design method and cross-electrospinning technology

The rapid development of piezoelectric sensors has been studied extensively, owing to their good flexibility, wearability, high sensitivity and low cost. However, some inorganic materials with good piezoelectricity cannot make sensors flexible, and the organic materials with good flexibility have a weak output electrical signal and low strength. In order to explore and optimize the preparation technology of piezoelectric sensors, a BaTiO3@polyacrylonitrile (PAN)/poly(vinylidene fluoride) (PVDF) nanofibrous composite membrane (NCM) was prepared by cross-electrospinning technology and the central combination design (CCD) method. The morphology, structure, hydrophobicity, mechanical properties and piezoelectricity of the BaTiO3@PAN/PVDF NCMs were investigated. The BaTiO3@PAN/PVDF NCMs had the better hydrophobicity and mechanical properties compared with the pure PAN/PVDF NCM. The 5BaTiO3@PAN/PVDF NCM designed by CCD had a more uniform fiber diameter, and a more stable output voltage with a 46% improvement. With the help of cross-electrospinning technology and the CCD method, the NCM will be outstanding for the development of fabricating flexible wearable piezoelectric sensors.

A Short Review of Advances in MOF Glass Membranes for Gas Adsorption and Separation

The phenomenon of melting in metal–organic frameworks (MOFs) has recently garnered attention. Crystalline MOF materials can be transformed into an amorphous glassy state through melt-quenching treatment. The resulting MOF glass structure eliminates grain boundaries and retains short-range order while exhibiting long-range disorder. Based on these properties, it emerges as a promising candidate for high-performance separation membranes. MOF glass membranes exhibit permanent and accessible porosity, allowing for selective adsorption of different gas species. This review summarizes the melting mechanism of MOFs and explores the impact of ligands and metal ions on glassy MOFs. Additionally, it presents an analysis of the diverse classes of MOF glass composites, outlining their structures and properties, which are conducive to gas adsorption and separation. The absence of inter-crystalline defects in the structures, coupled with their distinctive mechanical properties, renders them highly promising for industrial gas separation applications. Furthermore, this review provides a summary of recent research on MOF glass composite membranes for gas adsorption and separation. It also addresses the challenges associated with membrane production and suggests future research directions.

Preparing gelatin-containing polycaprolactone / polylactic acid nanofibrous membranes for periodontal tissue regeneration using side-by-side electrospinning technology.

Electrospinning technology has recently attracted increased attention in the biomedical field, and preparing various cellulose nanofibril membranes for periodontal tissue regeneration has unique advantages. However, the characteristics of using a single material tend to make it challenging to satisfy the requirements for a periodontal barrier film, and the production of composite fibrous membranes frequently impacts the quality of the final fiber membrane due to the influence of miscibility between different materials. In this study, nanofibrous membranes composed of polylactic acid (PLA) and polycaprolactone (PCL) fibers were fabricated using side-by-side electrospinning. Different concentrations of gelatin were added to the fiber membranes to improve their hydrophilic properties. The morphological structure of the different films as well as their composition, wettability and mechanical characteristics were examined. The results show that PCL/PLA dual-fibrous composite membranes with an appropriate amount of gelatin ensures sufficient mechanical strength while obtaining improved hydrophilic properties. The viability of L929 fibroblasts was evaluated using CCK-8 assays, and cell adhesion on the scaffolds was confirmed by scanning electron microscopy and by immunofluorescence assays. The results demonstrated that none of the fibrous membranes were toxic to cells and the addition of gelatin improved cell adhesion to those membranes. Based on our findings, adding 30% gelatin to the membrane may be the most appropriate content for periodontal tissue regeneration, considering the scaffold's mechanical qualities, hydrophilic properties and biocompatibility. In addition, the PCL-gelatin/PLA-gelatin dual-fibrous membranes prepared using side-by-side electrospinning technology have potential applications for tissue engineering.

Toward Self-Healing Coatings: Bacterial Survival and Calcium Carbonate Precipitation in Acrylic and Styrene–Acrylic Model Paint Films

Engineered living materials (ELMs) incorporate living material to provide a gain of function over existing materials, such as self-repair. The use of bacteria in ELMs has been studied extensively in concrete, where repair can be facilitated by bacterial ureolytic calcium carbonate (CaCO3) precipitation; however, the study of bacteria in other construction materials is limited. We examined the ability of bacterial species to survive in common latex binder chemistries, a model paint formulation, and through the film-forming process. The longest survival was by bacterial spores of Bacillus simplex str. GGC-P6A, which survive in latex emulsions, a liquid coating composition, and in a dried film for >28 days. Surprisingly, our data show that non-spore-forming Escherichia coli survive at least 15 days in liquid composition, which appear to be influenced by the composition of the outer membrane, nutrient scavenging, and the ability to metabolize toxic acrylate. Spores of GGC-P6A were shown to grow in solid paint films from sites of damage, resulting in crack filling through carbonate precipitation, demonstrating the potential for self-repair through microbially mediated CaCO3 precipitation without directed pH modification. These data suggest that a range of bacterial species, in particular members of Bacilli, may facilitate new applications of bio-augmented, self-healing coating systems.

Phase angle at bioelectric impedance analysis is associated with detrimental sperm quality in idiopathic male infertility: a preliminary clinical study.

In 2020, 38% of adults were affected by obesity, while infertility globally affected 1 in 6 people at some stage of their lives.Body mass index (BMI) provides an easy but occasionally inaccurate estimation of body composition. To achieve a more precise assessment, bioelectric impedance analysis serves as a validated tool that administers electrical energy through surface electrodes. Phase angle as a function of the relationship between tissues resistance and reactance, is a trustworthy predictor of body composition and cell membrane integrity. We aim to assess whether there is an association between phase angle and seminal parameters, as well as sperm DNA fragmentation percentage. Semen samples of 520 idiopathic infertile patients were analyzed according to 2021 World Health Organization guidelines and evaluated for sperm DNA fragmentation rate. Each participants underwent bioelectric impedance analysis. Median age was 40 years old, median BMI was 26.3 kg/m2, median phase angle was 6.2°. In the logistic regression analysis adjusted for age and total intracorporeal water, phase angle (continuous) was significantly associated with oligozoospermia (odds ratio [OR]:0.4; p<0.01) and sperm morphology (OR: 0.65; p=0.05) and slightly with sperm DNA fragmentation (OR: 0.98; p=0.07). In subgroup analysis, the logistic regression analysis adjusted for the mentioned parameters showed that a phase angle between 6.2 and 7 (°) (OR: 0.63; p=0.02) and >7 (°) (OR: 0.12; p<0.01) were associated with a reduced risk of oligozoospermia compared to values <6.2 (°). Similarly, a phase angle between 6.2 and 7 (°) (OR: 0.57; p< 0.01 and OR: 0.58; p= 0.01) and PA > 7 (°) (OR: 0.12; p= 0.03 and OR: 0.21; p< 0.01) were associated with a reduced risk of lower sperm concentration and lower total sperm count, respectively, compared to a phase angle < 6.2 (°). Our study suggests a negative association between phase angle and detrimental sperm parameters in male idiopathic infertility.

Unsealed Piezoelectric MEMS Speaker with Rigid-Flexible Composite Membrane

Abstract In this paper, we propose an unsealed piezoelectric microelectromechanical systems (MEMS) speaker with rigid-flexible composite membrane, which can eliminate the membrane separation and the vibration displacement limitation at high driving voltage compared to that with the sealed rigid-flexible coupling membrane demonstrated in our previous work. Measurements performed on encapsulated prototypes mounted to an artificial ear simulator have revealed that in the human audible range of 20 Hz-20 kHz, higher than 68.5 dB SPL are obtained at 2 V, and greater than 89.6 dB SPLs are achieved at 10 V. Moreover, the SPL distribution and effective SPLs at each moment when playing the same song exhibit similar characteristics to those of a commercial electromagnetic one. This piezoelectric MEMS speaker achieves high SPLs meeting the basic hearing needs of the human, and will have excellent prospects for future wearable audio electronics.&amp;#xD;

Multi-strategy dynamic cross-linking to prepare EGCG-loaded multifunctional Pickering emulsion/α-cyclodextrin/konjac glucomannan composite films for ultra-durable preservation of perishable fruits

Developing multifunctional films with antibacterial, antioxidant, and sustained-release properties is a robust strategy for preventing contamination of perishable fruits by foodborne microorganisms. This study engineered a sustained-release biodegradable antibacterial film loaded with EGCG (Pickering emulsion (PE)/α-Cyclodextrin (α-CD)/Konjac glucomannan (KGM)) through multi-strategy cross-linking for fruit preservation. EGCG is stabilized using PE and incorporated into the α-CD/KGM inclusion compound; the unique structure of α-CD enhances EGCG encapsulation, while KGM provides the film toughness and surface adhesion. The composite film's physicochemical properties, antioxidant, bacteriostatic and biodegradability were studied. Results showed that Pickering emulsions with 3 % oil phase exhibited excellent stability. Moreover, α-CD introduction increased the loading and sustained release of EGCG from the film, and its concentration significantly affected the light transmission, thermal stability, mechanical strength, mechanical characteristics and antioxidant capacity of the composite membrane. Antioxidant and antimicrobial activities of the composite film increased significantly with increasing α-CD concentration. Application of the film to tomatoes and strawberries effectively inhibited Escherichia coli and Staphylococcus aureus growth, prolonging the shelf-life of the fruits. Notably, the composite film exhibits superior biodegradability in soil. This EGCG-loaded PE/α-CD/KGM composite film is anticipated to be a multifunctional antimicrobial preservation material with sustained-release properties and biodegradable for perishable food applications.

Ternary composites of poly(vinylidene fluoride-co-hexafluoropropylene) with silver nanowires and titanium dioxide nanoparticles as separator membranes for lithium-ion batteries

In the realm of polymer composites, there is growing interest in the use of more than one filler for achieving multifunctional properties. In this work, a composite separator membrane has been developed for lithium-ion battery application, by incorporating conductive silver nanowires (AgNWs) and titanium dioxide (TiO2) nanoparticles into a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) polymer matrix. The composite membranes were manufactured by solvent casting and thermally induced phase separation, with total filler content varying up to 10 wt%. The ternary composites composites present improved mechanical characteristics, ionic conductivity and lithium transfer number compared to the neat polymer matrix. On the other hand, the filler type and content within the composite has little bearing on the morphology, polymer phase, or thermal stability. Once applied as a separator in lithium-ion batteries, the highest discharge capacity value was obtained for the 5 wt% AgNWs/5 wt% TiO2/PVDF-HFP membrane at different C-rates, benefiting from the synergetic effect from both fillers. This work demonstrates that higher battery performance can be achieved for next-generation lithium-ion batteries by using separator membranes based on ternary composites.

Fatty acid composition of erythrocyte membranes in carries of rs174544 polymorphism of FADS1 gene and rs174583 polymorphism of FADS2 gene from central region of the Russian Federation before and after supplementation of their diet with ω-3 PUFAs

Numerous publications have demonstrated that polymorphisms in FADS1 and FADS2 gene cluster influence the levels of long chain polyunsaturated fatty acids (LC PUFAs) synthesized in the body from essential precursors. They can be consumed through the diet as well. These LC PUFAs perform important plastic and regulatory functions in the body. The associations between the polymorphisms of FADS genes and the fatty acid (FA) composition of the body with some inflammatory and chronic diseases were shown. To date, very few studies in the Russian Federation researched the distribution of polymorphic variants in FADS1 and FADS2 genes and no studies examined the effects of these polymorphisms on the level of FAs in tissues.So, the purpose of this paper was to study the frequency of genotypes and alleles of the rs174544 polymorphism of the FADS1 gene and the rs174583 polymorphism of the FADS2 gene and their influence on the FA composition of erythrocyte membranes in residents of the Central region of the Russian Federation (RF). Additionally, the effect of ω-3 PUFAs fortified food products on this composition was examined. MethodsThe study included 70 volunteers aged 23–69 years from Moscow region who provided informed consent. They were genotyped for rs174544 polymorphism of FADS1 gene and rs174583 polymorphism of FADS2 gene by real-time PCR. The participants of the study consumed fruit or vegetable smoothies enriched with either vegetable (chia seeds flour) or animal (fish oil flour) sources of ω-3 PUFAs for 1 month. The fatty acid composition of erythrocyte membranes in some of the volunteers was analysed using gas-chromatography before and after fortification of their diet with ω-3 PUFAs. Statistical analysis was performed using SPSS 23. ResultsThe frequency of genotypes and alleles of polymorphisms studied were similar to those published for the European region. For rs174544, the genotype frequencies were CC (61%), CA (29%), and AA (10%), frequency of allele A was 24%. For rs174583, the genotype frequencies were CC (51%), CT (39%), and TT (10%), frequency of allele T was 29%. Carriers of minor alleles of both polymorphisms studied had significantly higher levels of ω-6 and ω-3 LC PUFAs in erythrocyte membranes compared to those carrying other genotypes. This differs from the results of other studies where carriers of minor alleles as were shown to be slow converters of precursors to LC PUFAs. The reason of the discrepancy was most likely associated with the obesity and dietary preferences of our study participants who carry the minor alleles. Over the period of one-month consumption of food sources providing an additional intake of either 2 g/day ω-3 PUFAs from fish oil or 6.5 g/day of ω-3 PUFAs from chia seed flour markedly reduced the incorporation of ω-6 PUFAs into erythrocyte membranes in carriers of minor alleles. Additionally, there was an increase in the content of saturated palmitic acid in the membranes that noticeably changed the fatty acid composition of erythrocyte membranes. ConclusionOur results confirm the observation that blood fatty acid composition related to polymorphisms of FADS gene is highly influenced by BMI. The incorporation of ω-6 PUFAs into erythrocyte membranes decreases when the diet is fortified with ω-3 PUFAs. This decrease can help reduce the formation of pro-inflammatory eicosanoids and the risk of various inflammatory and chronic diseases, especially in carriers of minor alleles of the genetic polymorphisms studied.

Efficient Cr(VI) remediation by electrospun composite porous nanofibers incorporating biomass with metal oxides and metal-organic framework

To develop a highly efficient adsorbent to remediate and remove hexavalent chromium ions (Cr(VI)) from polluted water, cellulose acetate (CA) and chitosan (CS), along with metal oxides (titanium dioxide (TiO2) and ferroferric oxide (Fe3O4)), and a zirconium-based metal-organic framework (UiO-66) were used to fabricate the composite porous nanofiber membranes through electrospinning. The adsorption performance, influencing factors, adsorption kinetics and isotherms of composite nanofiber membranes were comprehensively investigated. The multi-layer membrane with interpenetrating nanofibers and surface functional groups enhanced the natural physical adsorption and provided potential chemical sites. The thermal stability was improved by introducing TiO2 and UiO-66. CA/CS/UiO-66 exhibited the highest adsorption capacity (118.81 mg g−1) and removal rate (60.76%), which were twice higher than those of the control. The correlation coefficients (R2) of all the composite nanofibers regressed by the Langmuir model were significantly higher than those by the Freundlich model. The pseudo-first-order kinetic curve of CA/CS composite nanofibers showed the highest R2 (0.973), demonstrating that the whole adsorption process involved a combination of strong physical adsorption and weak chemical adsorption by the amino groups of CS. However, the R2 values of the pseudo-second-order kinetic model increased after incorporating TiO2, Fe3O4, and UiO-66 into the CA/CS composite nanofiber membranes since an enhanced chemical reaction with Cr (VI) occured during the adsorption

MXene/Ag3PO4 modified PVDF composite membranes for efficient interfacial evaporation and photodegradation

Solar-powered interface evaporation is considered a promising technology to obtain freshwater from non-potable water by using sustainable solar energy. However, research on combining the photocatalytic effect with solar interfacial evaporation technology to go for photothermal conversion materials with full solar spectrum utilization for photothermal and photodegradation capabilities is still scarce. Due to the unique optical properties of MXene, a novel MXene/Ag3PO4-based membrane with synergistic photothermal and photocatalytic effects was developed from the perspective of practical applications such as water purification, photodegradation of organic dyes and antibacterial properties. In this paper, polyvinylidene fluoride (PVDF) and carbon black (CB) were used as the substrate, calcium carbonate (CaCO3) and hydrochloric acid (HCl) were selected as the pore-forming agent for hydrophilic modification, and MXene/Ag3PO4 serves as the photocatalyst. The prepared composite polyvinylidene fluoride membrane (PCC-MXene/Ag3PO4) with Schottky junction, possesses a rich pore structure, abundant water molecule transport channels, high light absorption ability, and low thermal conductivity, which lead to a good performance in solar interface evaporation, photodegradation and antibacterial. The superhydrophobicity and floatability of the nanosponges in water enable them to continuously pump water, which greatly promotes the dissolution of salt accumulation. With the help of porous nanosponges, PCC-MXene/Ag3PO4 exhibits excellent evaporation stability and salt resistance under 1 kW m−2 solar irradiation, as well as photodegradation of organic dyes. In addition, the PCC-MXene/Ag3PO4 membrane has the properties of self-buoyancy, electrical conductivity, and superior flexibility. Therefore, considering the simple preparation method and fine performances, the PCC-MXene/Ag3PO4 mixed membrane has great application potential in the study of interface evaporation, photodegradation of organic dyes, and antibacterial properties.

Robust design of reinforced superhydrophobic FEP-SiO2@PTFE hollow fiber membrane for waste lubricating oils treatment

The shortage of petroleum resources brings the regeneration of used lubricating oils (ULOs) to a major issue, and hence the superhydrophobic membranes attract extensive attention derived from lotus-effect and capillary forces. In this paper, a superhydrophobic FEP-SiO2@PTFE hollow fiber composite membrane (HFCM) based on a facile step-by-step adhesive bonding method with a water contact angle up to 154.1°. The multilayered structure with superhydrophobic separation layer, microporous structure transition layer, and high strength supporting layer could be constructed. The lubricant permeate flux of membrane was as high as 814.5 L·m−2·h−1·bar−1 at 100 °C, with separation efficiencies of 99.3 % and 98.9 % for lubricants containing activated carbon and SiO2, respectively. Meanwhile, the flux of the membrane was stabilized at 430.9 L·m−2·h−1·bar−1 after 200 h of operation, and showed an initial permeation of 680.1 L·m−2·h−1·bar−1 after 5 cycles. Prominent mechanical properties and thermal-resistance (breaking strength of about 165.0 MPa, thermal decomposition temperature was up to 380℃) are another excellent performance of the membrane. As a result, the membrane provided another preferred option for the recycling of heavy oils, such as ULOs, at high temperatures or in various harsh environments.

Hydroxyapatite/polyamide 12 composite membrane as implant in intracorporeal sites

To evaluate the angiogenic and osteoinductive ability of implant consisting of hydroxyapatite powder incorporated into polyamide 12 membrane, thirty rats had this implant concomitantly placed at three intracorporeal sites (subcutaneous, omentum, and femur periosteum). Dosages of liver enzymes, urea, and creatinine serics demonstrated absence of hepatotoxicity and nephrotoxicity. Bone marrow samples, analyzed by the micronucleus test, demonstrated absence of toxicogenetic potential. The intracorporeal sites were assessed by light microscopy, indicating that the polymorphonuclear cells decreased in the omentum and femur periosteum, but not in the subcutaneous. The implants adhered to the femur periosteum between the 7th and 30th postoperative days. The periosteum thickness decreased on the 7th postoperative day. The vascularization decreased on all the postoperative days. In the femur periosteum, vascularization increased between the 7th and 21st. Calcium deposition in the omentum and femur periosteum was verified from the 7th day, without difference on later days. Subcutaneously, calcium deposition areas increased along time. By scanning electron microscopy was detected calcium and phosphorus deposition from the 7th day. Subcutaneous aggregation of these minerals became more evident on the 15th and 30th day, but the difference was not significant in the other intracorporeal sites. Subcutaneously, mineral organization was greater on the 15th postoperative day. In the omentum and femur periosteum, there was no difference along time. In conclusion, the implant did not display hepatotoxicity, nephrotoxicity, or genotoxicity, and stimulated deposition, aggregation, and organization of bone precursors from the very 7th postoperative day, which suggested that they have osteogenic and osteoinductive potential.